This book provides a solid overview of, and antidotes for, the most common reasons we make mistakes. Some of the more common reasons for mistakes (antidotes) include overconfidence (be less confident), unrecognized biases (take a step back to identify what is influencing your decision) and familiarity (have someone else take a look at your your project). Hallinan keeps the whole book light, but meaningful and includes many, often humorous, examples.
Interesting tidbit: Patients who had a reversible version of a surgery performed were more likely to be less happy than patients who underwent the permanent version of the surgery. Hallinan cites Loewenstein: "Hope impedes adaptation." In other words, as long as we have a chance, we resist adapting even if it means sacrificing our own happiness.